FIG. 1 is a view of a portion 10 of a sea surface 12 in which several platforms in the form of ships are disposed. In FIG. 1, a flotilla 14 of friendly ships includes ships 16, 18, and 20. Ships 16, 18, and 20 each bear sensors, such as radar, infrared sensors, optical sensors, or the like, which sense the presence of the other ships of flotilla 14, and which also sense the presence of aircraft in the vicinity, represented by an aircraft 22. The sensing of aircraft such as 22 by the ships of flotilla 14 is represented in FIG. 1 by “lightning bolt” symbols 24 and 26. The ships 16, 18, and 20 of flotilla 14 communicate among themselves by means of a communication network N, inter-ship portions of which are designated by lightning bolt symbols N1, N2, and N3. Such networks are sometimes known as “tactical” networks. It should be understood that the interplatform or intership network N may include many different signal paths, which variously include digital and analog portions, portions which are encrypted and other portions of which are not encrypted, and which traverse various paths, possibly including a path (not illustrated) extending through a satellite 36.
Each of the sensors of ships 16, 18, and 20 of flotilla 14 makes its own assessment of the sensor signals which its own sensors generate, and distributes the assessed information (or possibly some raw information from some sensors) over the network N among the ships of the flotilla. Thus, each ship of flotilla 14 has access to all the information from the various ships of the flotilla.
From the location of flotilla 14 of FIG. 1, a hostile ship 30 is over the horizon, and therefore may be invisible to the sensors of the flotilla 14. A friendly ship 32 is illustrated as being in the general vicinity of hostile ship 30, sufficiently so that its sensors can sense the hostile ship, as suggested by lightning bolt 34. Friendly ship 32 also senses aircraft 22 as represented by lightning bolt 38.
When friendly ship 32 “joins” the flotilla 14, as by joining network N, it is desirable that the information sensed by friendly ship 32 be made available over network N to the various ships 16, 18, and 20 of flotilla 14, and that the information sensed by the ships of the flotilla be made available to friendly ship 32. When ship 32 joins the flotilla 14, additional “target” information is made available over the network to the various ships. It is desirable to quickly and accurately rationalize the coordinate systems of the flotilla and of friendly ship 32 so that the information which is “new” to each platform can effectively use the information, as by orchestrating a response to the presence of hostile ship 30.
The sensors of the various ships of flotilla 14 of FIG. 1 produce data at a prodigious rate. Radar systems, for example, may recurrently scan hundreds of square miles of surface and the volume above it, producing data, possibly in the hundreds or thousands of megabytes per second. Since the inter-ship network N of FIG. 1, including at least paths N1, N2, and N3, has a finite bandwidth and must handle traffic other than sensor data, congestion can occur in the network. Congestion can, if not controlled, result in failure of the network to convey all of the data to all the nodes in a prompt fashion. In the context of potential warfare, such a failure can cause fatal lapses in data.
One conventional way to moderate the information traversing the inter-ship network N is for the operator of the radar or other sensor to “turn off” one or more targets or categories of targets. For example, in the presence of a great deal of sensor data, he may “turn off” the friendly targets, so that data pertaining to targets deemed friendly is or are not transmitted over the network. Another possibility is to turn off transmission of data pertaining to commercial airflights, as not being of immediate interest. Other classes of targets, or specific targets, can be identified for non-transmission over the network. It will be appreciated that it is possible for targets previously deemed to be friendly to be determined to be hostile, but the blocking of data transmission may inadvertently continue.
Improved techniques for network traffic management are desired.